1. Technical Field of the Invention
This invention relates to an improved stacked drop generator apparatus for ink jet printing.
2. Description of the Prior Art
Prior art generators for ink jet printing were bulky in size compared to the drop size produced. Consequently, the number of drop generators per printed character was physically limited. However, instead of decreasing the drop generator size to achieve closer spacing between ink drops, prior ink jet printers reduced the space between drops by increasing the size of the drop. As a result of the larger drop size, character definition and print quality are lessened.
Many ink jet printers have failed to successfully address the problem of fluid dribbling from the exit port once the jet has been energized to expel ink. The fluid, under static pressure in the ink reservoir and awaiting expulsion, was under no restraining force to inhibit leakage out the exit port.
The present invention promotes printed character definition and quality by utilizing the small size of the drop generator. More generators may be stacked to print each character. This feature permits a smaller drop size, better defined characters, and improved printing quality. In addition, the invention uses a deformable device to generate a pressure wave pulse through the printing fluid or ink. This wave expels a drop of fluid from a fluid filled cavity through an exit port. A reverse deformation of the device is then induced to withdraw the fluid at the exit port back into the fluid cavity. Consequently, an ink drop is generated and expelled on demand and ink dribbling from the exit port between drop generations is inhibited.